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database/sql: add support for multiple result sets
Many database systems allow returning multiple result sets in a single query. This can be useful when dealing with many intermediate results on the server and there is a need to return more then one arity of data to the client. Fixes #12382 Change-Id: I480a9ac6dadfc8743e0ba8b6d868ccf8442a9ca1 Reviewed-on: https://go-review.googlesource.com/30592 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Daniel Theophanes
Brad Fitzpatrick
parent
be48aa3f3a
commit
86b2f29676
5 changed files with 335 additions and 88 deletions
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@ -36,6 +36,8 @@ var _ = log.Printf
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// Any of these can be preceded by PANIC|<method>|, to cause the
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// named method on fakeStmt to panic.
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//
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// Multiple of these can be combined when separated with a semicolon.
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//
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// When opening a fakeDriver's database, it starts empty with no
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// tables. All tables and data are stored in memory only.
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type fakeDriver struct {
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@ -109,6 +111,8 @@ type fakeStmt struct {
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table string
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panic string
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next *fakeStmt // used for returning multiple results.
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closed bool
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colName []string // used by CREATE, INSERT, SELECT (selected columns)
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@ -377,7 +381,7 @@ func errf(msg string, args ...interface{}) error {
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// parts are table|selectCol1,selectCol2|whereCol=?,whereCol2=?
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// (note that where columns must always contain ? marks,
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// just a limitation for fakedb)
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func (c *fakeConn) prepareSelect(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
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func (c *fakeConn) prepareSelect(stmt *fakeStmt, parts []string) (*fakeStmt, error) {
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if len(parts) != 3 {
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stmt.Close()
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return nil, errf("invalid SELECT syntax with %d parts; want 3", len(parts))
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@ -411,7 +415,7 @@ func (c *fakeConn) prepareSelect(stmt *fakeStmt, parts []string) (driver.Stmt, e
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}
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// parts are table|col=type,col2=type2
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func (c *fakeConn) prepareCreate(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
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func (c *fakeConn) prepareCreate(stmt *fakeStmt, parts []string) (*fakeStmt, error) {
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if len(parts) != 2 {
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stmt.Close()
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return nil, errf("invalid CREATE syntax with %d parts; want 2", len(parts))
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@ -430,7 +434,7 @@ func (c *fakeConn) prepareCreate(stmt *fakeStmt, parts []string) (driver.Stmt, e
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}
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// parts are table|col=?,col2=val
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func (c *fakeConn) prepareInsert(stmt *fakeStmt, parts []string) (driver.Stmt, error) {
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func (c *fakeConn) prepareInsert(stmt *fakeStmt, parts []string) (*fakeStmt, error) {
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if len(parts) != 2 {
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stmt.Close()
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return nil, errf("invalid INSERT syntax with %d parts; want 2", len(parts))
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@ -492,38 +496,52 @@ func (c *fakeConn) Prepare(query string) (driver.Stmt, error) {
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return nil, driver.ErrBadConn
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}
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parts := strings.Split(query, "|")
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if len(parts) < 1 {
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return nil, errf("empty query")
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}
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stmt := &fakeStmt{q: query, c: c}
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if len(parts) >= 3 && parts[0] == "PANIC" {
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stmt.panic = parts[1]
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parts = parts[2:]
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}
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cmd := parts[0]
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stmt.cmd = cmd
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parts = parts[1:]
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var firstStmt, prev *fakeStmt
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for _, query := range strings.Split(query, ";") {
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parts := strings.Split(query, "|")
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if len(parts) < 1 {
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return nil, errf("empty query")
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}
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stmt := &fakeStmt{q: query, c: c}
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if firstStmt == nil {
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firstStmt = stmt
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}
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if len(parts) >= 3 && parts[0] == "PANIC" {
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stmt.panic = parts[1]
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parts = parts[2:]
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}
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cmd := parts[0]
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stmt.cmd = cmd
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parts = parts[1:]
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c.incrStat(&c.stmtsMade)
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switch cmd {
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case "WIPE":
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// Nothing
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case "SELECT":
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return c.prepareSelect(stmt, parts)
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case "CREATE":
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return c.prepareCreate(stmt, parts)
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case "INSERT":
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return c.prepareInsert(stmt, parts)
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case "NOSERT":
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// Do all the prep-work like for an INSERT but don't actually insert the row.
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// Used for some of the concurrent tests.
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return c.prepareInsert(stmt, parts)
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default:
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stmt.Close()
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return nil, errf("unsupported command type %q", cmd)
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c.incrStat(&c.stmtsMade)
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var err error
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switch cmd {
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case "WIPE":
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// Nothing
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case "SELECT":
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stmt, err = c.prepareSelect(stmt, parts)
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case "CREATE":
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stmt, err = c.prepareCreate(stmt, parts)
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case "INSERT":
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stmt, err = c.prepareInsert(stmt, parts)
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case "NOSERT":
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// Do all the prep-work like for an INSERT but don't actually insert the row.
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// Used for some of the concurrent tests.
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stmt, err = c.prepareInsert(stmt, parts)
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default:
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stmt.Close()
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return nil, errf("unsupported command type %q", cmd)
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}
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if err != nil {
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return nil, err
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}
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if prev != nil {
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prev.next = stmt
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}
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prev = stmt
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}
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return stmt, nil
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return firstStmt, nil
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}
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func (s *fakeStmt) ColumnConverter(idx int) driver.ValueConverter {
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@ -550,6 +568,9 @@ func (s *fakeStmt) Close() error {
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s.c.incrStat(&s.c.stmtsClosed)
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s.closed = true
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}
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if s.next != nil {
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s.next.Close()
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}
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return nil
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}
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@ -667,64 +688,80 @@ func (s *fakeStmt) Query(args []driver.Value) (driver.Rows, error) {
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panic("error in pkg db; should only get here if size is correct")
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}
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db.mu.Lock()
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t, ok := db.table(s.table)
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db.mu.Unlock()
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if !ok {
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return nil, fmt.Errorf("fakedb: table %q doesn't exist", s.table)
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}
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setMRows := make([][]*row, 0, 1)
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setColumns := make([][]string, 0, 1)
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if s.table == "magicquery" {
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if len(s.whereCol) == 2 && s.whereCol[0] == "op" && s.whereCol[1] == "millis" {
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if args[0] == "sleep" {
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time.Sleep(time.Duration(args[1].(int64)) * time.Millisecond)
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for {
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db.mu.Lock()
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t, ok := db.table(s.table)
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db.mu.Unlock()
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if !ok {
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return nil, fmt.Errorf("fakedb: table %q doesn't exist", s.table)
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}
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if s.table == "magicquery" {
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if len(s.whereCol) == 2 && s.whereCol[0] == "op" && s.whereCol[1] == "millis" {
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if args[0] == "sleep" {
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time.Sleep(time.Duration(args[1].(int64)) * time.Millisecond)
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}
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}
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}
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}
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t.mu.Lock()
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defer t.mu.Unlock()
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t.mu.Lock()
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colIdx := make(map[string]int) // select column name -> column index in table
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for _, name := range s.colName {
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idx := t.columnIndex(name)
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if idx == -1 {
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return nil, fmt.Errorf("fakedb: unknown column name %q", name)
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}
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colIdx[name] = idx
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}
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mrows := []*row{}
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rows:
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for _, trow := range t.rows {
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// Process the where clause, skipping non-match rows. This is lazy
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// and just uses fmt.Sprintf("%v") to test equality. Good enough
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// for test code.
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for widx, wcol := range s.whereCol {
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idx := t.columnIndex(wcol)
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colIdx := make(map[string]int) // select column name -> column index in table
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for _, name := range s.colName {
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idx := t.columnIndex(name)
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if idx == -1 {
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return nil, fmt.Errorf("db: invalid where clause column %q", wcol)
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}
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tcol := trow.cols[idx]
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if bs, ok := tcol.([]byte); ok {
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// lazy hack to avoid sprintf %v on a []byte
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tcol = string(bs)
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}
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if fmt.Sprintf("%v", tcol) != fmt.Sprintf("%v", args[widx]) {
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continue rows
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t.mu.Unlock()
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return nil, fmt.Errorf("fakedb: unknown column name %q", name)
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}
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colIdx[name] = idx
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}
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mrow := &row{cols: make([]interface{}, len(s.colName))}
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for seli, name := range s.colName {
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mrow.cols[seli] = trow.cols[colIdx[name]]
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mrows := []*row{}
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rows:
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for _, trow := range t.rows {
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// Process the where clause, skipping non-match rows. This is lazy
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// and just uses fmt.Sprintf("%v") to test equality. Good enough
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// for test code.
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for widx, wcol := range s.whereCol {
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idx := t.columnIndex(wcol)
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if idx == -1 {
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t.mu.Unlock()
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return nil, fmt.Errorf("db: invalid where clause column %q", wcol)
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}
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tcol := trow.cols[idx]
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if bs, ok := tcol.([]byte); ok {
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// lazy hack to avoid sprintf %v on a []byte
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tcol = string(bs)
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}
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if fmt.Sprintf("%v", tcol) != fmt.Sprintf("%v", args[widx]) {
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continue rows
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}
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}
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mrow := &row{cols: make([]interface{}, len(s.colName))}
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for seli, name := range s.colName {
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mrow.cols[seli] = trow.cols[colIdx[name]]
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}
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mrows = append(mrows, mrow)
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}
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mrows = append(mrows, mrow)
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t.mu.Unlock()
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setMRows = append(setMRows, mrows)
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setColumns = append(setColumns, s.colName)
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if s.next == nil {
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break
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}
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s = s.next
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}
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cursor := &rowsCursor{
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pos: -1,
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rows: mrows,
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cols: s.colName,
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posRow: -1,
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rows: setMRows,
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cols: setColumns,
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errPos: -1,
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}
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return cursor, nil
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@ -760,9 +797,10 @@ func (tx *fakeTx) Rollback() error {
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}
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type rowsCursor struct {
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cols []string
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pos int
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rows []*row
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cols [][]string
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posSet int
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posRow int
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rows [][]*row
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closed bool
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// errPos and err are for making Next return early with error.
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@ -786,7 +824,7 @@ func (rc *rowsCursor) Close() error {
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}
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func (rc *rowsCursor) Columns() []string {
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return rc.cols
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return rc.cols[rc.posSet]
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}
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var rowsCursorNextHook func(dest []driver.Value) error
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@ -799,14 +837,14 @@ func (rc *rowsCursor) Next(dest []driver.Value) error {
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if rc.closed {
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return errors.New("fakedb: cursor is closed")
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}
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rc.pos++
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if rc.pos == rc.errPos {
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rc.posRow++
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if rc.posRow == rc.errPos {
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return rc.err
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}
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if rc.pos >= len(rc.rows) {
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if rc.posRow >= len(rc.rows[rc.posSet]) {
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return io.EOF // per interface spec
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}
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for i, v := range rc.rows[rc.pos].cols {
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for i, v := range rc.rows[rc.posSet][rc.posRow].cols {
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// TODO(bradfitz): convert to subset types? naah, I
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// think the subset types should only be input to
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// driver, but the sql package should be able to handle
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@ -831,6 +869,19 @@ func (rc *rowsCursor) Next(dest []driver.Value) error {
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return nil
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}
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func (rc *rowsCursor) HasNextResultSet() bool {
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return rc.posSet < len(rc.rows)-1
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}
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func (rc *rowsCursor) NextResultSet() error {
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if rc.HasNextResultSet() {
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rc.posSet++
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rc.posRow = -1
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return nil
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}
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return io.EOF // Per interface spec.
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}
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// fakeDriverString is like driver.String, but indirects pointers like
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// DefaultValueConverter.
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//
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